1. Field of the Invention
The present invention relates to a connector with a partial connection detecting function and a water preventing function.
2. Description of the Related Art
Prior art connectors that are used in essential circuits of an airbag or like device are provided with a means for preventing a partial connection of female and male connectors to prevent an erroneous operation of the device. One such prior art connector is disclosed in Japanese Unexamined Patent Publication No. 11-111390 and is shown in FIG. 19 of this application. The prior art connector of FIG. 19 includes a female housing 1. A spring unit 2 is disposed in the female housing 1 and comprises a coil spring 2A and a spring pressing member 2B. The prior art connector further includes a male housing 4. The male housing 4 includes a receptacle 5, and a rib 5A projects from an outer surface of the receptacle 5. When the connection of the housings 1 and 4 is started, the rib 5A pushes the spring pressing member 2B to gradually compress the coil spring 2A. If the connecting operation is interrupted halfway, the housings 1 and 4 are separated by a spring force accumulated in the coil spring 2A, thereby preventing the housings 1 and 4 from being held in a partly connected condition.
Some of the above-described prior art connectors also must be watertight. To achieve a watertight connection, a rubber ring 6 is fitted on the outer circumferential surface of a back end of an inner tubular portion 3 of the female housing 1 so that the rubber ring 6 is sealed to the inner circumferential surface of the receptacle 5 of the male housing 4.
There has been a gradually increasing demand to decrease the size of watertight connectors that have a partial connection detecting function. Accordingly, it has been considered to make such a connector smaller by providing the spring unit 2 in an inwardly retracted position with respect to a radial direction and by deleting the rib 5A. Thus, the spring pressing member 2B would be pushed by an end edge of the receptacle 5. Additionally, an attempt could be made to retract the spring unit 2 to a position where the spring unit 2 overlaps the rubber ring 6 in radial direction. This construction would require the spring unit 2 to be provided behind the mount position of the rubber ring 6, as shown in FIG. 20. However, if the position of the spring unit 2 is displaced backward with respect to a connecting direction, the coil spring 2A can be compressed only after the receptacle 5 of the male housing 4 has been inserted relatively deeply. Thus, the compression of the coil spring 2A that exists when the connecting operation is interrupted halfway may not be sufficient to separate the terminal fittings in the housings 1 and 4 completely. Consequently, an electrical connection test may mistakenly detect that the connectors have been connected properly even though they are connected only partly.
A compression of the coil spring 2A at an early stage of the connecting operation conceivably could avoid the above-described problems. Thus, it may be considered to extend the receptacle 5 of the male housing 4 forward as much as the spring unit 2 is displaced backward. However, such an arrangement makes the entire connector larger in the connecting direction, and therefore is not a realistic option. On the other hand, it may be considered to select a material having a high rigidity for the coil spring 2A. Thus, a spring force that is large enough to separate the housings could be obtained even with a small degree of compression. However, this requires a larger force to connect the housings 1 and 4, thereby adversely affecting the connecting operation. As a result, the prior art does not provide and acceptable solution to the need for a small watertight connector that is capable of detecting an incomplete connection.
In view of the above, it is an object of the present invention to provide an improved connector having reduced overall dimensions but allowing for a good waterproof function.